Plating metals



Patented Mn. 8, 1927,

UNITED T TES";

TENT OFFICE.

-BEBTBAND S. sumns, OIBPOB'I HUBOIT,IIGHIGA1d' ASSIQR 'OR m LOCOKOTIVE 1331111111. 00., OF OHICAGQ, ILLIROIS, A CORPORATION 01' um.

name 'mi'rus.

No Drawing.

My invention relates to the electrodeposition of lead or allo s or mixtures thereof with other metals. 7 y invention is of particular utility in the plating of lead on iron objects of articles such as iron pipe which is exposed to corrosion by acids, etc. It has become common practice, for example to so coat iron and steel pipes which are required to withstand the action of acids, etc., to

10 which they are exposed by reason of being embedded in the earth. It is essential for satisfactory results that such pipes be more or less resistent to the actionof both acid and alkaline solutions. The pipe if coated with a dense adherent film of lead is fairly satisfactory though somewhat susceptible to the action of alkalies. I have found that when nickel is deposited with the lead. a coating muchimore resistent to both alkali 2 0 and acid solutions is obtained and the coating is'harder and of better color.

If as commonly the lead is deposited from an acid or neutral bath it is diflicult to ob-- tain a uniformly dense and adherent coat of lead and moreover the coatin is contaminated with more or lessiron salts from the bath which quickly oxidize and stain the pipe and rusty color. If, however, the,lead is plated from an alkaline bath this dilliculty is overcome and a dense, bright, at-- .tractive coating is secured. The lead may be plated alone from the alkaline bath in case a lead coating alone is desired.- In case,

however, an alloy or,mixture of lead with another metal such as nickel is preferred,

' the two metals are plated together from an alkali bath containing salts of both "'metals. r I

' I have found that a suitable solution for t depositing lead alone maybe made as follows: Dissolve 3 parts of commercial lead acetate. in 16 partswate'r and separately dissolve 6 parts of commercial causticsoda in 16 parts of water and slowly add the lead solution to the caustic soda solution. When the two solutions have been thoroughly incorpora'ted, add-about -part'of commercial If gluel The electrolyte thus formed may be used for plating in the usual manner;

5 1 c e a-h d r a d m e s ant coatin the first of which I dissolve 1 part of not limited to Application filed February 9, 1924. Serial lie. 891,882.

ing is used I prefer to deposit nickel with 'the lead. For this purpose I form an electi'olyte by forming separately four solutions,

commercial lead acetate in 8 parts of water; in the, second, 4 parts of commercial caustic soda in 8 parts of water; in the third, 2 parts of commercial cyanide of soda or potash in 8 parts of water, and in the fourth, 4 parts of a soluble salt of nickel such as the chloride, sulphate or nitrate orany of 'the well known double salts of nickel in 8 parts of water. The lead, acetate solution is slowly added to the causticsoda solution while stirring, until the lead is dissolved. The nickel salt' solution is slowly added to the cyanide solution until the nickel salt is I I completely dissolved inthe latter. Then the two resultant solutions are added together to make the electrolyte read desired a small amount of g ue may be added to the electrolyte to im wire the character of E i the coating. The bat may then be used in the ord nary manner for plating the articles to be coated. I have found that with either of the above electrolytes a current density from one to two amperes pensquare -foot may be used','-the length of the operation depending u n the thickness of coat desired. In plating from the lead-nickel electrolyte I prefer to use two anodes, of lead and .nickel, respectively, which referably have about equal surfaces. If esired for. the-purpose of securing greater u'niformity of deposit, the anodes may be muls8 tiplied. Furthermorewhile the proportions of materials given above are satisfactory. they may' be varied within wide limits and more orless of the advantages of my invention obtained and therefore my invention is such proportions. Iclaim; w

1. As an article-of manufacture, an ar ticle of'iron covered withan electro-(lcposited coating of lead and nickel. ,jv

2. A bath for .electro depositing-a"mixture of lead and nickel, said bath consist- E cyamde-of nickel. v c

' BEB-TRAND s. SUMMERS.

.1 j .l v

for plating. If 70 i of p um or an alkali metal and I 

